Exhaust gas recirculation systems are used in internal combustion engines to reduce air pollution problems. Exhaust gas is recirculated via a recirculation passageway to the intake passage an internal combustion engine to reduce generation of unwanted pollutants by the engine. Typically, a recirculation regulating valve is provided in the recirculation passageway. This valve controls the rate of recirculation in response to the vacuum generated by the engine in the intake passage.
One problem noted with such systems is that the regulating valve is unable to quickly shut off exhaust gas recirculation fully upon deceleration of the engine. This results in the combustion in the engine being unstable. This can result in a significant increase in the unburned hydrocarbon content of the exhaust gas.
Thus, there is a need for a exhaust gas recirculation regulating system designed to close the recirculation regulating valve immediately at when the operator decelerates the engine.